The invention relates to a device for processing images with an image forming set-up for producing images which are split up into elements, a memory for the storage of image information by elements, a subtraction circuit for the subtraction of image information from each image element of previously determined image information in the corresponding image element and a playback device for reproducing the information determined via the subtraction circuit from each image element.
Such a medical examination device has already been proposed in a paper by R. A. Kruger et al. published in the bimonthly journal "Optical Engineering", Vol. 17, No. 6, November/December 1978, pp. 652-657. In the examination device a fluoroscopic image is converted via an image intensifier and image pick-up chain into a video-signal which is then digitized. The digitized image is then stored in one of three video-memories. Each video-memory must have the capacity to hold summed image information emanating from a number of fluoroscopic images. The function of the three video-memories changes cyclically. A weighted image is determined from two memories which reproduces, with emphasis, the differences between the consecutive images stored in the two memories. An image information processing method such as this is termed time-interval differential imaging by the authors of the paper. The third memory is regenerated while the differences in the two memories are being determined. For this reason the device described in the paper must contain three video-memories. This makes it expensive.